The Korean War began in 1950 when North Korean forces crossed the 38th parallel that divided North and South Korea, invading South Korea in an attempt to reunify the country under communist rule. The United States led UN forces to defend South Korea against the invasion by North Korean forces equipped with Soviet tanks. Although UN forces recaptured Seoul and pushed into North Korea, China entered the war on North Korea's side, leading to a stalemate near the 38th parallel and over 4 million military and civilian casualties before an armistice was signed in 1953, leaving Korea still divided along the parallel.